Systems and Methods of Sensing Temperature of Air in a Passenger Area of a Fuselage

ABSTRACT

An example temperature sensing device includes an air distribution inlet through which primary air is blown into via an environmental control system, a cabin air inlet through which secondary air enters from a passenger area of a fuselage and the cabin air inlet is coupled to the air distribution inlet through a duct and the secondary air is passively drawn into the cabin air inlet and to the duct due to a pressure difference present in the duct, and a temperature sensor coupled to the duct and positioned downstream of the cabin air inlet along an airflow path of the secondary air so as to be exposed to the secondary air drawn in through the cabin air inlet and flowing through the duct.

FIELD

The present disclosure relates generally to systems and methods to sensetemperature of air in a passenger area of a fuselage, and moreparticularly, to temperature sensing devices and aircraft systemsincluding a temperature sensor positioned downstream of a cabin airinlet to be exposed to air drawn in through the cabin air inlet andflowing through the duct.

BACKGROUND

Modern passenger transport aircraft typically operate at elevatedaltitudes in order to avoid weather and to obtain other advantagesgenerally associated with high altitude flight. Accordingly, suchaircraft are equipped with an environmental control system that providespressurized and temperature controlled air to passengers within a cabinof the aircraft. Briefly and in general terms, the environmental controlsystem typically extracts air at an elevated temperature and pressurefrom a compressor section of one or more of the engines of the aircraft,suitably conditions the extracted air, and distributes the conditionedair to the cabin to provide a comfortable environment for the flightcrew and passengers within the aircraft.

Air temperatures are generally closely regulated to achieve a desiredcomfort level to flight crew and passengers. Accordingly, the flightdeck and the passenger compartment generally include various temperaturesensing devices positioned in flight deck and passenger compartmentsthat are operable to control the system to admit additional cold airwhen additional cooling is desired, and to correspondingly addadditional higher temperature air when additional heating is desired.

An example temperature sensing device includes a powered fan to drawcabin air into an air duct that contains a temperature sensor. The fanrequires an electrical power source, and can add to complexity of thedevice. There is a desire for an improved temperature sensing devicethat operates without a powered fan to draw cabin air into an air ductthat contains a temperature sensor.

SUMMARY

In an example, a temperature sensing device is described that includesan air distribution inlet through which primary air is blown into via anenvironmental control system, a cabin air inlet through which secondaryair enters from a passenger area of a fuselage and the cabin air inletis coupled to the air distribution inlet through a duct and thesecondary air is passively drawn into the cabin air inlet and to theduct due to a pressure difference present in the duct, and a temperaturesensor coupled to the duct and positioned downstream of the cabin airinlet along an airflow path of the secondary air so as to be exposed tothe secondary air drawn in through the cabin air inlet and flowingthrough the duct.

In another example, an aircraft system is described that includes aninterior panel of a fuselage including an air grille, and a temperaturesensing device. The temperature sensing device includes an airdistribution inlet through which primary air is blown into via anenvironmental control system, a cabin air inlet coupled to the airgrille and through which secondary air enters from a passenger area ofthe fuselage and the cabin air inlet is coupled to the air distributioninlet through a duct and the secondary air is passively drawn into thecabin air inlet and to the duct due to a pressure difference present inthe duct, and a temperature sensor coupled to the duct and positioneddownstream of the cabin air inlet along an airflow path of the secondaryair so as to be exposed to the secondary air drawn in through the cabinair inlet and flowing through the duct.

In another example, a method of sensing temperature of air in apassenger area of a fuselage is described. The method includes blowingprimary air through an air distribution inlet via an environmentalcontrol system, drawing secondary air from a passenger area of afuselage into a cabin air inlet and the cabin air inlet is coupled tothe air distribution inlet through a duct and the secondary air ispassively drawn into the cabin air inlet and to the duct due to apressure difference present in the duct, and sensing, by a temperaturesensor coupled to the duct and positioned downstream of the cabin airinlet along an airflow path of the secondary air, a temperature of thesecondary air drawn in through the cabin air inlet and flowing throughthe duct.

The features, functions, and advantages that have been discussed can beachieved independently in various examples or combined in yet otherexamples. Further details of the examples can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

The novel features believed characteristic of the illustrative examplesare set forth in the appended claims. The illustrative examples,however, as well as a preferred mode of use, further objectives anddescriptions thereof, will best be understood by reference to thefollowing detailed description of an illustrative example of the presentdisclosure when read in conjunction with the accompanying drawings,wherein:

FIG. 1 illustrates an aircraft, according to an example implementation.

FIG. 2 illustrates a view inside the fuselage, aft facing, of apassenger area, according to an example implementation.

FIG. 3A illustrates a view inside the fuselage, aft facing, of aninternal area above the passenger area, according to an exampleimplementation.

FIG. 3B illustrates another view inside the fuselage, aft facing, of aninternal area above the passenger area, according to an exampleimplementation.

FIG. 4 illustrates a perspective view of an aircraft system including anexample of the temperature sensing device, according to an exampleimplementation.

FIG. 5 illustrates a cross-sectional view of an example of thetemperature sensing device, according to an example implementation.

FIG. 6 illustrates a perspective view of another example of the aircraftsystem including another example of the temperature sensing device,according to an example implementation.

FIG. 7 illustrates a cross-sectional view of an example of the aircraftsystem in FIG. 6, according to an example implementation.

FIG. 8 illustrates a bottom view of an example of the aircraft system inFIG. 6, according to an example implementation.

FIG. 9 illustrates another perspective view of the aircraft system shownin FIGS. 6-8, according to an example implementation.

FIG. 10 illustrates a front view of the aircraft system shown in FIGS.6-8 according to an example implementation.

FIG. 11 illustrates a side view of the aircraft system of FIG. 6installed in the aircraft on a right hand side (aft facing), of aninternal area above the passenger area, according to an exampleimplementation.

FIG. 12 illustrates a perspective view of the aircraft system of FIG. 6installed in the aircraft on a right hand side (aft facing), of aninternal area above the passenger area, according to an exampleimplementation.

FIG. 13 illustrates a side view of the aircraft system of FIG. 6installed in the aircraft on a left hand side (aft facing), of aninternal area above the passenger area, according to an exampleimplementation.

FIG. 14 shows a flowchart of an example of a method of sensingtemperature of air in the passenger area of the fuselage, according toan example implementation.

FIG. 15 shows a flowchart of an example function that is performed withthe method shown in FIG. 14, according to an example implementation.

FIG. 16 shows another flowchart of an example function that is performedwith the method shown in FIG. 14, according to an exampleimplementation.

FIG. 17 shows another flowchart of an example function that is performedwith the method shown in FIG. 14, according to an exampleimplementation.

DETAILED DESCRIPTION

Disclosed examples will now be described more fully hereinafter withreference to the accompanying drawings, in which some, but not all ofthe disclosed examples are shown. Indeed, several different examples aredescribed and should not be construed as limited to the examples setforth herein. Rather, these examples are described so that thisdisclosure will be thorough and complete and will fully convey the scopeof the disclosure to those skilled in the art.

Within examples, a temperature sensing device is described that includesan air distribution inlet through which primary air is blown into via anenvironmental control system, a cabin air inlet through which secondaryair enters from a passenger area of a fuselage and the secondary air ispassively drawn into the cabin air inlet and to the duct due to apressure difference present in the duct, and a temperature sensorcoupled to the duct and positioned downstream of the cabin air inletalong an airflow path of the secondary air so as to be exposed to thesecondary air drawn in through the cabin air inlet and flowing throughthe duct.

Within examples, the temperature sensing device uses air flow from theenvironmental control system to draw cabin air across the temperaturesensor without the use of a fan. Geometry of the duct and interiorbarrels direct airflow in a way that creates low pressure inside theduct. The low pressure draws cabin air across the temperature sensor.The temperature sensor then measures cabin temperature for theenvironmental control system.

Referring now to the figures, FIG. 1 illustrates an aircraft 100,according to an example implementation. The aircraft 100 includes a nose102, wings 104 a-b, a fuselage 106, a tail 108, and engines 110 a-b.Although FIG. 1 illustrates an example of a commercial passengeraircraft, other types of aircraft are used with examples describedherein. In addition, depending on the type of aircraft fewer or moreengines are included.

FIG. 2 illustrates a view inside the fuselage 106, aft facing, of apassenger area 112, according to an example implementation. Thepassenger area 112 in the fuselage 106 includes seating on either sideof the aircraft 100. In the example shown in FIG. 2, the aircraft 100includes two rows with one row on a right hand side of the aircraft 100and the other row on a left hand side of the aircraft 100. Overheadstowage bins 114 are included along a ceiling of the fuselage 106 alongboth rows. Above seating of the passenger area 112 are interior panels,such as interior panel 116, of the fuselage 106 including an air grille118. Air from the passenger area 112 of the fuselage 106 is drawn intothe air grille 118 and is directed to a temperature sensing device 122(see, e.g., FIG. 3A) to determine a temperature of the passenger area112 of the fuselage 106.

FIG. 3A illustrates a view inside the fuselage 106, aft facing, of aninternal area above the passenger area 112, according to an exampleimplementation. FIG. 3A illustrates a fuselage perimeter 120 of thefuselage 106, and a temperature sensing device 122 is mounted to asurface of the interior panel 116 opposite the passenger area 112 of thefuselage 106. Additional interior panels 124, 126, and 128 are shown andlabeled for reference. Although only one temperature sensing device 122is illustrated for the interior panel 116, a temperature sensing devicecan be included on each interior panel, on every other interior panel,or in any arrangement on the interior panels. Thus, more than onetemperature sensing device 122 can be included in the fuselage 106, anda number as well as arrangement of temperature sensing devices dependson a size and configuration of the aircraft 100, for example.

The temperature sensing device 122 is connected to an environmentalcontrol system 130 through a hose 132. As shown in FIG. 3A, thearrangement of the hose 132 is one example, and the hose 132 may bearranged differently, as described below. The environmental controlsystem 130 receives compressed, clean air from compressor stages of theengines 110 a-b or when on the ground from an auxiliary power unit (APU)or a ground source. The environmental control system 130 supplies orblows air into the temperature sensing device 122. The environmentalcontrol system 130 also supplies or blows air into gasper grilles abovepassenger seats (not shown) to blow air into the passenger area 112 inthe fuselage 106. Within an example operation, gaspers are temporarilyturned off during certain phases of flight (e.g., during take-off andclimb) when a load on the engines 110 a-b from bleed-air demands isminimized.

The temperature sensing device 122 is utilized to determine atemperature inside the passenger area 112 of the fuselage. Thedetermined temperature is used to control the environmental controlsystem 130 air output to admit additional cold air when additionalcooling is desired, and to correspondingly add additional highertemperature air when additional heating is desired.

FIG. 3B illustrates another perspective view inside the fuselage 106 ofan internal area above the passenger area 112, according to an exampleimplementation. In FIG. 3B, the hose 132 arrangement is shown moreclearly as connecting the temperature sensing device 122 to theenvironmental control system 130, for example.

FIG. 4 illustrates a perspective view of an aircraft system 140including an example of the temperature sensing device 122, according toan example implementation. FIG. 5 illustrates a cross-sectional view ofan example of the temperature sensing device 122, according to anexample implementation.

The aircraft system 140 includes the interior panel 116 of the fuselage106 including the air grille 118, and the temperature sensing device122. The temperature sensing device 122 includes an air distributioninlet 144 through which primary air 145 is blown into via theenvironmental control system 130, and a cabin air inlet 146 throughwhich secondary air 147 enters from the passenger area 112 of thefuselage 106, and the cabin air inlet 146 is coupled to the airdistribution inlet 144 through a duct 148. The secondary air 147 ispassively drawn into the cabin air inlet 146 and to the duct 148 due toa pressure difference present in the duct 148. In an example, the cabinair inlet 146 is coupled to the air grille 118 of the interior panel116, and the secondary air 147 enters the cabin air inlet 146 throughthe air grille 118.

The temperature sensing device 122 also includes a temperature sensor150 coupled to the duct 148 and positioned downstream of the cabin airinlet 146 along an airflow path of the secondary air 147 so as to beexposed to the secondary air 147 drawn in through the cabin air inlet146 and flowing through the duct 148. The duct 148 includes an opening152 into which a portion of the temperature sensor 150 is inserted so asto be exposed to the secondary air 147 drawn in through the cabin airinlet 146 and flowing through the duct 148.

As mentioned, a pressure difference between air pressure in thepassenger area 112 of the fuselage 106 and air pressure inside the duct148 is present. This is due to the primary air 145 being blown into theair distribution inlet 144. The duct 148 also has nozzles 154 a-b andthe pressure difference is further caused by increased airflow velocitythrough the nozzles 154 a-b and then through the barrel of the duct 148.The nozzles 154 a-b include, for example, small tubes inside the duct148.

In some examples, the duct 148 includes barrels 156 a-b coupled to thenozzles 154 a-b. The nozzles 154 a-b and the barrels 156 a-b are coupledto the air distribution inlet 144 to direct airflow so as to create alower pressure inside the duct 148 as compared to the passenger area 112in the fuselage 106 to further draw the secondary air 147 into the cabinair inlet 146. In one example, the nozzles 154 a-b and the barrels 156a-b are additively manufactured components. Similarly, in one example,the air distribution inlet 144, the cabin air inlet 146, and the duct148 all include additively manufactured components.

The secondary air 147 enters the cabin air inlet 146 and travels alongan airflow path through the duct 148. In the example shown in FIG. 4, aportion 158 of the duct 148 that connects to the cabin air inlet 146 isan angled portion. However, the duct 148 can alternatively include astraight non-angled structural pathway as well. The secondary air 147drawn into the cabin air inlet 146 to the duct mixes with the primaryair 145 blown into the air distribution inlet 144 after the secondaryair 147 drawn into the cabin air inlet 146 to the duct 148 passes by thetemperature sensor 150 (e.g., shown as mixed air 149). In one example,the temperature sensing device 122 also includes an exhaust 160 coupledto the duct 148 to exhaust the primary air 145 mixed with the secondaryair 147 to an area between the passenger area 112 of the fuselage 106and the fuselage perimeter 120 of the fuselage 106.

In operation, the temperature sensing device 122 uses airflow from theenvironmental control system 130 to draw cabin air across thetemperature sensor 150, which measures cabin temperature for theenvironmental control system 130. The secondary air 147 is drawn intothe cabin air inlet 146 due to air ejector principles. For example, adrop in pressure is caused by increased velocity through the nozzles 154a-b (e.g., a restriction) that then pulls (entrains) additionalsecondary air through the cabin air inlet 146. A total entrained airflowis due to the Venturi Effect and the entrainment ratio.

Airflow momentum is transferred from the primary air 145 to thesecondary air 147. To do so, the primary air 145 is accelerated in thenozzles 154 a-b (e.g., a smaller diameter area). The accelerated primaryair 145 mixes and transfers momentum to the secondary air 147 along thebarrels 156 a-b. This creates a pressure difference that draws thesecondary air 147 into the duct 148 and the barrels 156 a-b. In oneexample, a single nozzle is used to cause an increase in velocity, witha single barrel section for mixing, although the single barrel wouldneed to be a sufficient length to allow for adequate momentum transferto generate necessary secondary airflow for the application. To reducelength and enable the temperature sensing device 122 to fit overhead thepassenger area 112 of the fuselage 106, multiple nozzles and barrels areused in the temperature sensing device 122. For example, the nozzles 154a-b and the barrels 156 a-b are used in parallel.

The duct 148 can be tuned to optimize airflow that is drawn in and overthe temperature sensor 150 by changing a number of the nozzles 154 a-band the barrels 156 a-b, for example.

In some examples, the length of the barrels 156 a-b need to provideenough distance for the momentum transfer to take place. A diameter andlength combination of the barrels 156 a-b can be determined such thatthe air velocity pressure at the exhaust 160 is small compared to a gagestatic pressure at the cabin air inlet 146 to provide a highest pressurerise in the secondary airflow path.

Within examples, the configuration of the duct 148 and the nozzles 154a-b and the barrels 156 a-b direct airflow to create low pressure insidethe duct 148 that draws the secondary air 147 into the cabin air inlet146 and past the temperature sensor 150. The temperature sensing device122 has no moving parts, and therefore does not require any electricityor related hardware (other than to power the temperature sensor 150).

The temperature sensing device 122 can be used to replace a typicalpowered fan device used to draw cabin air using the gasper air system.Thus, the temperature sensing device 122 has many benefits including,for instance, lower cost and ease of assembly (due to fewer parts), andalso decreased noise (compared to conventional temperature sensingdevices) with no fan operating. Further, with no moving parts, there isless of a chance to have less than optimal performance of thetemperature sensing device. In addition, in examples, the temperaturesensing device 122 is additively manufactured making production moreefficient and in real-time.

In FIG. 4, the temperature sensing device 122 is mounted to a surface ofthe interior panel 116 using a mount 162. Any type of mount can be used.In one example, the temperature sensing device 122 and the interiorpanel 116 are an integral part. For instance, the temperature sensingdevice 122 and the interior panel 116 can be additively manufacturedtogether.

FIG. 6 illustrates a perspective view of another example of the aircraftsystem 140 including another example of the temperature sensing device122, according to an example implementation. FIG. 7 illustrates across-sectional view of an example of the aircraft system 140 in FIG. 6,according to an example implementation. FIG. 8 illustrates a bottom viewof an example of the aircraft system 140 in FIG. 6, according to anexample implementation. FIG. 9 illustrates another perspective view ofthe aircraft system 140 shown in FIGS. 6-8, according to an exampleimplementation. FIG. 10 illustrates a front view of the aircraft system140 shown in FIGS. 6-8 according to an example implementation.

The temperature sensing device 122 shown in FIGS. 6-10 is coupled to theinterior panel 116 of the fuselage 106 including the air grille 118 (asshown in the bottom view in FIG. 8), and the temperature sensing device122 includes the same components as described above with respect toFIGS. 4-5. However, the temperature sensing device 122 shown in FIGS.6-8 includes the duct 148 arranged to be angled with respect to a planeof the interior panel 116 (whereas the duct 148 in the temperaturesensing device 122 shown in FIGS. 4-5 is substantially horizontal to aplane of the interior panel 116).

Thus, the duct 148 of the temperature sensing device 122 shown in FIGS.6-10 includes two angled portions, namely the portion 158 of the duct148 that connects to the cabin air inlet 146 is an angled portion and asecond angled portion 164 is included as well. The configuration of theexample of the temperature sensing device 122 shown in FIGS. 6-10enables the temperature sensing device 122 to fit into smaller spaces,for example. With this configuration, the duct 148 and the nozzles 154a-b and the barrels 156 a-b are shorter in length, and thus, twoadditional nozzles and barrels 156 c-d are included (as seen in theviews illustrated in FIGS. 9-10). With the four nozzles and barrels 156a-d, it enables a sufficient difference in pressure to draw thesecondary air 147 (e.g., cabin air) into the cabin air inlet 146 byblowing the primary air 145 into the air distribution inlet 144.

Thus, the duct 148 can be tuned to include fewer or more nozzles andbarrels to cause a lesser or greater pressure difference to change howmuch of the secondary air 147 is drawn into the cabin air inlet 146. Itis desirable for the temperature sensor 150 to sense a temperature ofair that is representative of the cabin, and thus, a flow of thesecondary air 147 needs to be of a sufficient volume of air for arepresentation of a temperature of the cabin.

Thus, the primary air 145 is blown into the air distribution inlet 144,and then mixes with the secondary air 147 that entered the cabin airinlet 146 from the passenger area 112 of the fuselage 106 and passed bythe temperature sensor 150 before mixing with the primary air 145. Themixed air 149 is output of the temperature sensing device 122 throughthe exhaust 160.

FIG. 11 illustrates a side view of the aircraft system 140 of FIG. 6installed in the aircraft on a right hand side (aft facing), accordingto an example implementation. FIG. 12 illustrates a perspective view ofthe aircraft system 140 of FIG. 6 installed in the aircraft on a righthand side (aft facing), according to an example implementation. FIG. 13illustrates a side view of the aircraft system 140 of FIG. 6 installedin the aircraft on a left hand side (aft facing), according to anexample implementation.

In FIGS. 11-13, it can be seen that the primary air 145 mixed with thesecondary air 147 is exhausted through the exhaust 160 to an areabetween the passenger area 112 of the fuselage 106 and the fuselageperimeter 120 of the fuselage 106. Generally, the mixed air 149 isexhausted in a ceiling panel area of the fuselage 106, for example. Theexhausted air can generally be routed in any direction as long as theexhausted air does not feed back into an area of the passenger area 112that is nearby the cabin air inlet 146, for example, that wouldrecirculate and impact temperatures of air being sampled.

FIGS. 12-13 illustrate the hose 132 connected to the air distributioninlet 144 to provide the primary air 145 into the temperature sensingdevice 122. The hose 132 is routed along the fuselage perimeter 120 tothe environmental control system 130 (not shown in FIGS. 12-13).

Although the aircraft system 140 is shown and described as beingpositioned in a ceiling of the fuselage 106 or above the passenger area112, the aircraft system 140 may alternatively be positioned in otherareas of the fuselage 106. In one example, the aircraft system 140 ispositioned in a galley area of the aircraft 100, in a floor panel of theaircraft 100, or in a side wall panel of the aircraft 100.

FIG. 14 shows a flowchart of an example of a method 200 of sensingtemperature of air in the passenger area 112 of the fuselage 106,according to an example implementation. Method 200 shown in FIG. 14presents an example of a method that could be used with the aircraft 100shown in FIG. 1, with the aircraft system 140 shown in FIGS. 4 and 6-10,or with the temperature sensing device 122 shown in FIGS. 3A-13, forexample. Further, devices or systems are used or configured to performlogical functions presented in FIG. 14. In some instances, components ofthe devices and/or systems are configured to perform the functions suchthat the components are actually configured and structured (withhardware and/or software) to enable such performance. In other examples,components of the devices and/or systems are arranged to be adapted to,capable of, or suited for performing the functions, such as whenoperated in a specific manner. Method 200 includes one or moreoperations, functions, or actions as illustrated by one or more ofblocks 202-206. Within examples, although the blocks are illustrated ina sequential order, these blocks are also able to be performed inparallel, and/or in a different order than those described herein. Also,the various blocks may be combined into fewer blocks, divided intoadditional blocks, and/or removed based upon the desired implementation.

It should be understood that for this and other processes and methodsdisclosed herein, flowcharts show functionality and operation of onepossible implementation of present examples. In this regard, each blockor portions of each block may represent a module, a segment, or aportion of program code, which includes one or more instructionsexecutable by a processor for implementing specific logical functions orsteps in the process. The program code is be stored on any type ofcomputer readable medium or data storage, for example, such as a storagedevice including a disk or hard drive. Further, the program code can beencoded on a computer-readable storage media in a machine-readableformat, or on other non-transitory media or articles of manufacture. Thecomputer readable medium may include non-transitory computer readablemedium or memory, for example, such as computer-readable media thatstores data for short periods of time like register memory, processorcache and Random Access Memory (RAM). The computer readable medium mayalso include non-transitory media, such as secondary or persistent longterm storage, like read only memory (ROM), optical or magnetic disks,compact-disc read only memory (CD-ROM), for example. The computerreadable media may also be any other volatile or non-volatile storagesystems. The computer readable medium may be considered a tangiblecomputer readable storage medium, for example.

In addition, each block or portions of each block in FIG. 14, and withinother processes and methods disclosed herein, may represent circuitrythat is wired to perform the specific logical functions in the process.Alternative implementations are included within the scope of theexamples of the present disclosure in which functions may be executedout of order from that shown or discussed, including substantiallyconcurrent or in reverse order, depending on the functionality involved,as would be understood by those reasonably skilled in the art.

At block 202, the method 200 includes blowing primary air 145 throughthe air distribution inlet 144 via the environmental control system 130.

At block 204, the method 200 includes drawing secondary air 147 from thepassenger area 112 of the fuselage 106 into the cabin air inlet 146, andthe cabin air inlet 146 is coupled to the air distribution inlet 144through the duct 148. The secondary air 147 is passively drawn into thecabin air inlet 146 and to the duct 148 due to a pressure differencepresent in the duct 148.

For instance, no fan is required to draw the secondary air 147 into thecabin air inlet 146. As compared with some existing systems, a fan isreplaced by an air pressure system, e.g., the environmental controlsystem, which blows primary air 145 into the air distribution inlet 144.Thus, pressurized air blown into the temperature sensing device 122draws air into the temperature sensing device 122 and past thetemperature sensor 150 in a passive manner.

FIG. 15 shows a flowchart of an example function that is performed withthe method 200 shown in FIG. 14, according to an example implementation.In some examples, as shown at block 208, the duct 148 has the nozzles154 a-b (or 154 a-d), and the method 200 also includes causing thepressure difference by increased airflow velocity through the nozzles154 a-b (or 154 a-d) of the duct 148.

FIG. 16 shows another flowchart of an example function that is performedwith the method 200 shown in FIG. 14, according to an exampleimplementation. In some examples, as shown at block 210, the duct 148includes the nozzles 154 a-b (or 154 a-d) and the barrels 156 a-b (or156 a-d) coupled to the air distribution inlet 144, and the method 200also includes creating a lower pressure inside the duct 148 as comparedto the passenger area 112 in the fuselage 106 by directing airflowthrough the nozzles 154 a-b (or 154 a-d) and the barrels 156 a-b (or 156a-d) in order to further draw the secondary air 147 into the cabin airinlet 146.

Referring back to FIG. 14, at block 206, the method 200 includessensing, by the temperature sensor 150 coupled to the duct 148 andpositioned downstream of the cabin air inlet 146 along an airflow pathof the secondary air 147, a temperature of the secondary air 147 drawnin through the cabin air inlet 146 and flowing through the duct 148.

FIG. 17 shows another flowchart of an example function that is performedwith the method 200 shown in FIG. 14, according to an exampleimplementation. In some examples, as shown at block 212, the method 200also includes mixing the secondary air 147 drawn into the cabin airinlet 146 to the duct 148 with the primary air 145 blown into the airdistribution inlet 144 after the secondary air 147 drawn into the cabinair inlet 146 to the duct 148 passes by the temperature sensor 150. Forexample, the two flows of air (i.e., primary air 145 and secondary air147) do not mix until after the secondary air 147 drawn in through thecabin air inlet 146 passes the temperature sensor 150. This allows thetemperature sensor 150 to detect air temperature of the secondary air147 (e.g., air temperature in the cabin of the fuselage 106) and not beaffected by the primary air 145 from the environmental control system130.

Within examples, the method 200 also includes exhausting the primary air145 mixed with the secondary air 147 to an area between the passengerarea 112 of the fuselage 106 and the fuselage perimeter 120 of thefuselage 106.

Using the aircraft system 140 described herein enables air temperaturesto be determined while providing a tamper proof temperature sensingdevice that is remotely located and out of sight from passengers.Further, since the temperature sensing device 122 does not include a fanto draw cabin air into an air duct that contains the temperature sensor150, the temperature sensing device 122 can operate with decreased noisecompared to conventional temperature sensing devices.

Note that although this disclosure has described use of the methods andsystems for use on aircraft, the same functions and device can applyequally to use of the methods and system on board any type of vehicle todraw air past a temperature sensor in a passive manner. The methods andsystems can also find use within non-vehicles or stationary areas aswell wherever sensing of air temperatures is desired.

By the term “substantially” and “about” used herein, it is meant thatthe recited characteristic, parameter, or value need not be achievedexactly, but that deviations or variations, including for example,tolerances, measurement error, measurement accuracy limitations andother factors known to skill in the art, may occur in amounts that donot preclude the effect the characteristic was intended to provide.

Different examples of the system(s), device(s), and method(s) disclosedherein include a variety of components, features, and functionalities.It should be understood that the various examples of the system(s),device(s), and method(s) disclosed herein include any of the components,features, and functionalities of any of the other examples of thesystem(s), device(s), and method(s) disclosed herein in any combinationor any sub-combination, and all of such possibilities are intended to bewithin the scope of the disclosure.

The description of the different advantageous arrangements has beenpresented for purposes of illustration and description, and is notintended to be exhaustive or limited to the examples in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different advantageous examplesdescribe different advantages as compared to other advantageousexamples. The example or examples selected are chosen and described inorder to best explain the principles of the examples, the practicalapplication, and to enable others of ordinary skill in the art tounderstand the disclosure for various examples with variousmodifications as are suited to the particular use contemplated.

What is claimed is:
 1. A temperature sensing device comprising: an airdistribution inlet through which primary air is blown into via anenvironmental control system; a cabin air inlet through which secondaryair enters from a passenger area of a fuselage, wherein the cabin airinlet is coupled to the air distribution inlet through a duct and thesecondary air is passively drawn into the cabin air inlet and to theduct due to a pressure difference present in the duct; and a temperaturesensor coupled to the duct and positioned downstream of the cabin airinlet along an airflow path of the secondary air so as to be exposed tothe secondary air drawn in through the cabin air inlet and flowingthrough the duct.
 2. The temperature sensing device of claim 1, whereinthe secondary air is drawn into the cabin air inlet due to air ejectorprinciples.
 3. The temperature sensing device of claim 1, wherein theduct has a nozzle and wherein the pressure difference is caused byincreased airflow velocity through the nozzle of the duct.
 4. Thetemperature sensing device of claim 1, wherein the duct comprises:barrels coupled to the air distribution inlet to direct airflow so as tocreate a lower pressure inside the duct as compared to the passengerarea of the fuselage to further draw the secondary air into the cabinair inlet.
 5. The temperature sensing device of claim 4, wherein thebarrels comprise additively manufactured components.
 6. The temperaturesensing device of claim 1, wherein the air distribution inlet, the cabinair inlet, and the duct comprise additively manufactured components. 7.The temperature sensing device of claim 1, wherein the duct comprises:an opening into which a portion of the temperature sensor is inserted soas to be exposed to the secondary air drawn in through the cabin airinlet and flowing through the duct.
 8. The temperature sensing device ofclaim 1, wherein a portion of the duct that connects to the cabin airinlet is an angled portion.
 9. The temperature sensing device of claim1, further comprising: an air grille coupled to the cabin air inletthrough which the secondary air enters from the passenger area of thefuselage.
 10. The temperature sensing device of claim 1, wherein thesecondary air drawn into the cabin air inlet to the duct mixes with theprimary air blown into the air distribution inlet after the secondaryair drawn into the cabin air inlet to the duct passes by the temperaturesensor.
 11. The temperature sensing device of claim 10, furthercomprising: an exhaust coupled to the duct to exhaust the primary airmixed with the secondary air to an area between the passenger area ofthe fuselage and a fuselage perimeter of the fuselage.
 12. An aircraftsystem comprising: an interior panel of a fuselage including an airgrille; and a temperature sensing device comprising: an air distributioninlet through which primary air is blown into via an environmentalcontrol system; a cabin air inlet coupled to the air grille and throughwhich secondary air enters from a passenger area of the fuselage,wherein the cabin air inlet is coupled to the air distribution inletthrough a duct and the secondary air is passively drawn into the cabinair inlet and to the duct due to a pressure difference present in theduct; and a temperature sensor coupled to the duct and positioneddownstream of the cabin air inlet along an airflow path of the secondaryair so as to be exposed to the secondary air drawn in through the cabinair inlet and flowing through the duct.
 13. The aircraft system of claim12, wherein the temperature sensing device is mounted to a surface ofthe interior panel opposite the passenger area of the fuselage.
 14. Theaircraft system of claim 12, wherein the duct comprises: barrels coupledto the air distribution inlet to direct airflow so as to create a lowerpressure inside the duct as compared to the passenger area in thefuselage to further draw the secondary air into the cabin air inlet. 15.The aircraft system of claim 12, wherein the duct comprises: an openinginto which a portion of the temperature sensor is inserted so as to beexposed to the secondary air drawn in through the cabin air inlet andflowing through the duct.
 16. A method of sensing temperature of air ina passenger area of a fuselage, the method comprising: blowing primaryair through an air distribution inlet via an environmental controlsystem; drawing secondary air from a passenger area of a fuselage into acabin air inlet, wherein the cabin air inlet is coupled to the airdistribution inlet through a duct and the secondary air is passivelydrawn into the cabin air inlet and to the duct due to a pressuredifference present in the duct; and sensing, by a temperature sensorcoupled to the duct and positioned downstream of the cabin air inletalong an airflow path of the secondary air, a temperature of thesecondary air drawn in through the cabin air inlet and flowing throughthe duct.
 17. The method of claim 16, wherein the duct has a nozzle, andwherein the method further comprises: causing the pressure difference byincreased airflow velocity through the nozzle of the duct.
 18. Themethod of claim 16, wherein the duct comprises nozzles and barrelscoupled to the air distribution inlet, and wherein the method furthercomprises: creating a lower pressure inside the duct as compared to thepassenger area in the fuselage by directing airflow through the nozzlesand barrels in order to further draw the secondary air into the cabinair inlet.
 19. The method of claim 16, further comprising: mixing thesecondary air drawn into the cabin air inlet to the duct with theprimary air blown into the air distribution inlet after the secondaryair drawn into the cabin air inlet to the duct passes by the temperaturesensor.
 20. The method of claim 19, further comprising: exhausting theprimary air mixed with the secondary air to an area between thepassenger area of the fuselage and a fuselage perimeter of the fuselage.